' 



SB 951 
.H55 




^^^^^^^HjJKi 



.-^^^ 




0' ^■ 



r^y 



'V ^<>...^^^ 













...^-^^ 



iv -^^ 




















■'■■■' 'n. _ < 
t 





















i'^^ 



• • o 






^O 



^ 



oV' 








U. S. I)Klv\R'rMKN'l- Ol- ACRICUL'I'URE, 

BUREAU UF CHEMISTRY BULLETIN NU. 82. 

H. \V. WIl.KV, ClllKl- UF UCKEAU. 



PARIS (JREI^N SPRAYING EXPIIHLMKNTS. 



BY 



.r. K. IIAVWOOD, 

('hicf lii>iectici<l<' (Hid A;/ri(~idlur(>l Walcr f.nhunitoni, 



In collaboration with the Division of Entomolog'y, XT. S. Department of Agriculture, anc". 

the agrricultural experiment stations of Maryland, New York, 

New Hampshire, Rhode Island, South 

Carolina, and Oregon. 




WA'SHIN(i TON: 

G O V E K N M K N T I' i; I N T 1 N ( ; ( ) F F I (^ E 



'37 



c,^^^^ 



w^ 



<> 



LETfER OF TRANSMITTAL 



U. S. Department or Agriculture, 

Bureau of Chemistry, 
Wasidmiton, D. C, March 19, lOOJ,.. 
Sir: I have the honor to transmit for your approval a report on a 
series of spraying experiments with Paris Green, prepared in the 
insecticide and ag-ricultural water laboratory of this Bureau, and to 
recommend its pu])lication as Bulletin No. 82 of the Bureau of Chem- 
istry. It is desired to. acknowledge especially the cooperation of the 
Division of P^ntomology and the contri])utions of the various experiment 
stations named, at which so large a part of the work was performed. 
The two half-tone plates express graphically one of the most important 
points made in the bulletin and are deemed of value in impressing 
the conclusions drawn in the text. 

Respectfullv, 

H. W. Wiley, Chief. 

Hon. James Wilson, 

Secretary of Agriculture. 



CONTENTS 



Page. 

Rea>son>s for the investigation 5 

Preliminary work at AVashington, D. C 8 

Plan of the experiment g 

Observations 9 

Summary of results 1 1 

Organization of cooperative wc^rk n 

Preparation of samples .■ 1 1 

Directions for spraying 12 

Report from the Maryland station _ 12 

Reixirt froni the New York station If, 

Report from the Rhode Island station 19 

Report from the South Carolina station 20 

Report from the New Hampshire station 23 

Report from. the Oregon .station 25 

Summary 3q 

3 



ILLUSTRATIONS. 



I'agt;. 
Platk I. Fijj;. 1. — Peach tree with foUa^e in minual condition, Kingston, 
R. I. Fig. 2. — Peacli trcc^ sprayed witli solntion No. 1, Avithont 

Hnie, Kingston, R. T 16 

II. Mg. 1. — Peach tree sprayed witli solution No. 2, with Ume, Kings- 
ton, K. I. Fig. 2. — Peach tree sprayed with solution No. (>, with- 
out lime, Kingston, E. 1 16 



PARIS GREEN SPRAYING EXPERIMENTS. 



REASONS FOR THE INVESTIGATION. 

Theso exporiiiKMits were uiKlort;ikeii to show how imich sohil)lo 
iirsenious oxid may ho prescMit in .s}inipl(>s of Pari.s (fr(H'M used for 
.spi-nyin*:- ])iirpos('s without injui-y to the foliage. As i> well known. 
Pari.s (irtHMi is coinposcHl of copper oxid. acetic acid, and arsenious 
oxid. eonil)ined as copppr-acoto-arsenite in the folh)wino- proportion.s: 

I'tT cent. 

Cupper oxid .S 1 . 29 

Arnenioiis oxid ilS. 65 

Acetic acid 10. Ofi 

Since this sut)stance is alway.s sold ujx)!! the market as a commercial 
rather than a cliemically })ure article, small amounts of im[)urities are 
alwa^'s ])resent. Amono- these may he mentioned sand, sodium sul- 
phat(\ and arsenious oxid. the last of which is not combined as it should 
be with th(> other constituents, but is present in the free state. It is 
to this impurity of Paris (rreen that the scoi'chino- pi-operties are 
usually ascribed. California has passed a law limitino- th(» amount of 
fre(^ arsenious oxid in Paris (ircen to 4 per cent, while New York's law 
limits the amount to M.."> per cent. In the other States. whei(» there 
are no laws u'overnino- the matter, the entomolooists usually considiM' 
4 per cent of fi"ee arsenious oxid to be the maxinunn amount allowable 
in Paris (ii-een u.schI for spraying-. 

It does not seem to have been g'enerally recognized by entomologists" 
and chemists that there may l)e three conditions of Paris Green which 
will cause a scorching of the foliage. 

(1) As indicated above, there may be a certain amount of arsenious 
oxid in Pari.s Green over and above that combined with the other con- 

'^'Marlatt in two articles (Insect Life, vol. vii, July, 1895, pp. 40.S-411, and bulletin 
No. (), Division of P>ntomoloo:y, September, 189(i, jip. :>0-8o) has recoirnized the first 
and tiiird conditions of Paris Green that may give rise to a scorching of the foliage, 
but not the second condition. 



6 PARIS GREEN SPRAYING EXPERIMENTS. 

stituents. This is "free" arsenious oxid and until recently it has been 
considered the only cause of a scorching of the foliage b}' Paris Green. 

(2) The greens may be poorly made so that the constituents are very 
loosely held together. When such greens are brought in conta<"t with 
water, especiall}' water containing carbon dioxid, theyiare soon broken 
up and arsenious oxid is set free. Even the best greens break up to 
some extent under such conditions, but the poorly made greens decora- 
pose much more rapidly. Note, then, the effect of such greens upon 
the foliage. First, the water of the spray would act at once on the 
green and set arsenious oxid free, then carbon dioxid would dissolve 
in the water and carry the decomposition of the green still further. 
But the matter would not end here, for the rain and dew both contain- 
ing carbon dioxid would also act upon the green and enough free 
arsenious oxid would soon collect to severely scorch the foliage. This 
would of course take place more slowl}^ with even the best greens, but 
unless the climatic conditions were very adverse, not enough free 
arsenious oxid would l)e apt to accumulate at one time to cause anj'^ 
serious damage. 

(3) The green ma}' ])e extremely tine. It is well known that even 
the l)est greens when ground to a very tine powder and applied to the 
foliage will scorch. This is dou])tless due to the fact that moi'e sur- 
face is exposed to the action of water, which may contain carbon 
dioxid, so that its decomposing action on the green is accelerated and 
enough free arsenious oxid soon gathers to cause serious damage. 
Avery and Beans'^' found that the ver}' best Paris Greens ol)tainable 
were slowly attacked l)y water, and ])y grinding the same gi-eens to a 
very line powder and suspending them in water the rate of decomposi- 
tion was enormously increased. They also found that carbon dioxid 
in the water increases the rapidity of decomposition. 

It is a very common occurrence to secure a connuercial Paris Green 
that scalds because of one of the first two causes — i. e., either by rea- 
son of the presence of free arsenious oxid or because it is poorly 
manufactured — but the writer has never found a commercial sample of 
green that scorched because it was in too tine a condition. In exper- 
imenting on the third method of scorching even the hnest samples of 
green found on the market had to l)e ground further })efore they 
would scorch ])y reason of minute division. 

It is thus seen that the chemist will be called upon to examine 
samples of green (1) for actual free arsenious oxid: (2) for arsenious 
oxid that may be easily set free on account of the instability of the 
compound. Methods of determining these two forms of solul)le arse- 
nious oxid have been devised during the last few years which, though 
not strictly accurate, will give results close enough for all practical 

«J. Amer. Chem. Sue, 23: 111. 



REASONS K(»R INVESTIGATION. 7 

purposes. Tlicsc mctluMls, willi the reason fof llicir adoplion, arr as 
follows: 

III (lot(>nniiiiiio- soluhio arsenic it is (nitlent that it would not l>e suf- 
Heient to extract the <>-reen for only 24 houi's with water, since in 
samples containing- free arscMiious acid as such, all of the arsenic does 
not ^"o into solution in that lenoth of time, and neither do samples that 
arc poorl}' made break up to any extent within twenty-four hours. 
The author has found that it takes from live to ten days, according- to 
the amount present, for all tiie free arsenious oxid to go into solution. 
It has also ])een found that badly made oreens are broken uj) enout^li 
durint>' the course of ten days to g-ivc some idea of their instability and 
that well-mad(> «-reens arc not broken up to any great extent during 
that length of time. It has therefore been thought best to determine 
the soluble ai\senious oxid in Paris Greens by extracting one part of the 
green with 1,()0() parts of cai'bon dioxid-free water foi- ten da3^s and 
at the end of this time determining the ai-senious oxid in an ali(|uot 
portion of the filtrate. This nu^thod shows whether the green con- 
tains a large quantity of free arsenious oxid or whethm- it is badly 
made, ])ut does not distinguish between the two. A lui^thod devised 
by Avery and Beans," however, allows us to aj)proximiitely determine 
the amount of free arsenious oxid present exclusive of that formed by 
the decomposition of the green. Therefore, l)y using both methods 
the chemist will ])e able to tell either the amount of free arsimious 
oxid actually present in the green or the amount that is apt to be 
present a short time aftei* spi-ayiiig. Both of these forms of soluble 
arsenious oxid are undoubtedly injurious, although pcriiaps not 
erpially so. 

These two distinct types of soluble arsenious oxid in connnercial 
Paris Green have not been pi'eviously recognized, and furthei'more 
when 4 per cent was adopted as the maxinuun amount of soluble arseni- 
ous oxid allowa])le in Piiris (xreen the extraction with water was con- 
tinu(Ml for a nuich shorter time, resulting in nuicli lowei' iigures for 
soluble arsenious oxid. It would appear, therefore, that investiga- 
tion along this line is needed'' to d(»termine tluMnaximum amount of 
soluble arsenious oxid. as found \)\ our present methods of analysis, 
that can be present in a Paris GrecMi in both foiins without danger of 
scorcliing. This investigation is an attempt to answei' the ([uestion 
under the first condition, i. e., when the soluble arsenious oxid is 
present in the free condition. It is hoped that in the near future 
experiments may be made on Paris Greens of the second type. 



«J. Amer. Cheiii. Soc, 23: 111. 

'' Valuable work upon the effect of arsenic ami arseiiite on ])iantH lian l)een ]ml)- 
llshed by (lillette, Woodworlli, P>ailey, Marlatt, and otliers, but not alon<^ tlie lines 
followed in this experiment. 



8 PARTS GREEN SPRAYING EXPERIMENTS. 

PRELIMINARY WORK AT WASHINGTON, D. C. 

PLAN OF THE EXPERIMENT. 

Preliminary work was begun during tiie early summer of 1902, and 
carried out in the following manner: A large ([uantit;;- of Paris Green, 
as pure as eould be obtained, was purchased and a determination made 
of the solul)le arsenious oxid by the ten-day water-extraction method. 
Then known quantities of perfectly pure arsenious oxid were added 
to different quantities of the green, so that samples of a definite arseni- 
ous oxid content were obtained. Each of these samples contained to 
1 pound of Paris Green the following amounts of soluble arsenious 
oxid: 

Per cent. 

No. 1 -4.29 

No. 2 ^-00 

No. 3 6.00 

No. 4 7. GO 

No. 5 8. 00 

Two sets of these samples were made up and applied in the follow- 
ing manner: 

Set 1. 

Treat one-half of each of 5 samples described above with 150 gallons of water, 
making 1 ])oniid to IJOO gallons, and si)ray delicate trees, sncli as peach tiees. 

Treat the other half of each of th(i 5 samples with 150 gallons of water, making 1 
pound to 300 gallons, and 1 pound of lime, and again spray delicate trees, such as 
peach trees. 

Set n. 

Treat one-half of each of above 5 samples with 80 gallons of water, making 1 pound 
to 100 gallons, and sju-ay hardy trees, such as apjile trees. 

Treat the other half of the 5 samples with 80 gallons of water, making 1 pound to 
160 gallons, and 1 i)ound of lime, and again spray hardy trees, such as apple trees. 

The dates of spraying and taking of observations and the duration 
of the experiment were carefully noted. 

With the aid of Mr. F. C. Pratt, an assistant in the Division of 
Entomology, the autlior sprayed young peach, apple, and pear trees, 
following very closely the directions outlined a])ove. The trees grew 
in the Agricultural Department grounds, and, unfortiniately. had been 
used before in various experiments upon insects and sprays, so that all 
of them were not in a perfectly healthy condition. Since they were tlie 
only trees available, and the investigation was only preliminary in 
character, to fix within wide limits the amount of soluble arsenic that 
can be endured ])y the trees, it was thought they would serve the pur- 
pose. The table on the next page, giving the weather conditions 
during the fii-st part of the experiment, is furnished l)y the United 
States Weather Bureau. 



PRKLIMINAHV OHSERVATIONa. 9 

Wi'dllirr (■iiiiiIIUdiis, W'fi.shiiujldu, I). C, June ^0 to Jul if L5, 1903. 



Date. 


Menu 
temper- 
ature. 


Precipita- 
tion. 


(iencral cliarac- 
ter of (lay. 


1902. 


° F. 


Inches. 




June 20 


73 


Trace. 


Partly cloudy. 


21 


73 


O.S.'i 


Cloudy. 


22 


(14 


.00 


Clear. 


23 


M 


Trace. 


Partly cloudy. 


24 


(!0 


.00 


Do. 


2f) 


t!4 


.01 


(near. 


2(; 


73 


1.37 


Do. 


27 


72 


.00 


Partly cloudy. 


28 


70 


.01 


Cloudy. 


29 


.HO 


. 03 


Partly cloudy. 


:!0 


m 


.31 


Cloudy. 


July 1 


(i.S 


".01 


(near. 


2 


72 


.00 


Do. 


3 


82 


.00 


Partly cloudy. 


4 


80 


Trace. 


Do. 


5 


84 


.00 


Do. 


6 


84 


Trace. 


Do. 


7 


74 


Trace. 


Cloudy. 


,S 


81 


.W) 


Partly cloudy. 


9 


82 


.00 


Do. 


10 


78 


.34 


Do. 


11 


70 


.00 


Clear. 


12 


70 


.00 


Do. 


13 


72 


.00 


Do. 


14 


79 


.00 


Do. 


15 


82 


.02 


Do. 



ajn the moniiuir. Ix'tdrc the trees were sprayed. 



OBSERVATIONS. 



The trees were first spniyed on fhine ^0. The next day a heav^y 
rain fell, which seemed to wash ofl' the Paris (xreen completely. After 
waiting- for 10 da3's — i. e., until -Fuly 1 — to see whether the trees 
would be affected, they were again sprayed, no damage being ob.served 
at that time. After the second spraying o])servations were made on 
the following dates: July 5, lo, IC, August 11. and September 18, 1902. 
With the peaches the results were somewhat irregular on account of 
the varying hardiness of the trees and the fact that some of them were 
attacked later in the season by in.sect pests; but a few g-eneral conclu- 

( sions can be draAvn. As one would expcK-t from previous ex})eriments, 
the peaches did not show any injury from the spray until after the Hrst 
considera))le rain, on July lo. 'riien the trees on which lime was not 
used were all more or less burned and partly defoliated, except the one 
sprayed with solution No. 3 (6 per cent of arsenious oxid). This tree 
was very hardy and was not injured in any Avay. The tree sprayed 

] with solution No. 1 (4.29 pei- cent of arsenious oxid). without lime, was 



10 PARIS GREEN SPRAYING EXPERIMENTS. 

not injured to a great extent, })ut a few leaves fell. The injuiy to trees 
when lime was used with tlu^ J^iris Green was not nearly so great as 
when lime was not used, which was to be expected. Those sprayed 
with solutions Nos. 1, 2, and 8 (4.29, 5, and 6 per cent of arsenious 
oxid), with lime, while showing a slight 3'ellowing, spotting, and fall- 
ing of the leaves, were not injured to any great extent, and the falling 
of the leaves soon ceased. All of the sprayed peach trees lost their 
leaves much earlier in the autumn than is common in and around 
Washington: but as all of the trees near by had been used in the experi- 
ment it was not possible to make any comparison with unspraj^ed trees 
to ascertain whether the premature ripening of the leaves was due to 
some other cause than the poison. 

The apple trees when sprayed with varying- strengths of arsenious 
oxid, without lime, all showed about 1 to 2 per cent of injur}'. A few 
leaves were curled and burned at the edges where the Paris Green had 
collected in the greatest quantities, but the injury was slight, and after 
these leaves fell the trees did not show that th(\v had been sprayed at 
all. All were in good condition and remained so throughout the sum- 
mer, except the one sprayed with solution No. 1, which died during 
August. . 

Th(^ same results were obtained on the trees sprayed with the ^'ari()us 
solutions after the addition of lime. None was seriously injured, and 
in al)out two weeks after the spraying no effects could l)e seen. In 
the case of the tree spraj^ed with solution No. 2, with lime, it was 
observed that a])out one-third of the leaves had fallen on September 18, 
but as the trees sprayed with much stronger solutions were in no way 
affected it appeared that the dropping of the leaves was not caused by 
the spray. It was noted in the case of trees sprayed both with and 
without lime that about one-half of them lost the greater part of their 
leaves hy Octol)er 12, which is rather earl}- in this climate. This was 
not true to so great an extent of the trees that had been sprayed with 
the addition of lime, but still there was a tendency in this direction. 
Four extremely hardy apple trees, sprayed with solutions Nos. 3 and 
4 (0 and 7 per c(>nt arsenious oxid), with lime, did not drop their leaves 
early, while two trees, not so hardy, that Avere sprayed with solutions 
Nos. 1 and 2 (1.21» and .5 per cent arsenious oxid) dropped over one- 
half of their leaves by October 12. It did not appear that the prema- 
ture dropping of the lea\'es in the autumn was accompanied by any 
permanent injury to the tree. 

The pear trees, in those cases in which no lime was used, had a few 
leaves burned on the edges at the tirst and second ol)servations, but 
these soon dropped off or withered away, and the trees were in excellent 
condition. In fact, it may be said that pear trees sprayed with any of 
the ti^e solutions without lime were practically unaffected, none being 
damaged to the extent of 2 per cent. Th(^ trees spra3^ed with any one 
of th(> solutions with lime were not scorched in the slightest degree. 



ORGANIZATION OF WORK. 11 

Toward the oiul of the season the ti(>e treated with sohition No. 1 (4.29 
jMM'cent of arseiiious oxid), without liiue, dicnl. and the tree tn^attul with 
solution No. 2 (f) per eent of arseiiious oxid), with lime, drojiped its 
foliao-o })reniatur(dy, but this was not attributed to the spray, since 
trees treated with much stronger solutions were in excellent condition, 
and. furthermore, t\\o injured trees appeared to liave lieen attac^kedhy 
pear-leaf l)lij>'ht, so that a lar^e iiumlxM' of lea\'(^s turned black and 
withered. 

SUMMARY OF RESULTS. 

Under tlu^ conditions prevailino- during- the early summer of 1im»l} 
at Washiiio-t()n, 1). {\, th(> following- conclusions may be di'jiwn: 

(f) If lime is not used peach tre(>s can not b(> sprayed Avitli Paris 
(Ireen containinij- even as little as 4.2i» per c<Mit of solul)l(> arseiiious 
oxid; if lime is used oreens containinj^- as much as (> pvv cent of solulile 
arsenious oxid may be used without causino' serious damage. 

(2) Apple trees may l)e sprayed with Paris (innMi containing as 
much as S per cent of solulile arsenious oxid, either with or without 
lime, without any immediate injury to the tree, although what the 
eti'ect might be in causing the trees to dro}) their leaves prematurely 
and expose^ the fruit has not bcuMi determined. 

(.")) Pear trees may lie sprayed with ]*aris (Ireen containing as much 
as S per c(Mit of soluble arsenious oxid, either with or without lime, 
without any injury to the tree. 

ORGANIZATION OF COOPERATIVE WORK. 

During the spring of 1903 the author addressed a letter to the ento- 
mologists of several of the experiment stations in different parts of the 
counti'v asking for their cooperation in a continuation of this work. 
Favorable replies were obtained from al)out t(Mi difl'erent stations, but 
reports were received only from the following: John Craig and II. K. 
Weed, Ithaca, N. Y.; C. M. Weed and J. L. Randall, Durham. N. II.: 
F. W. Card and A. E. Stenc, Kingston, R. I.; C. E. Cham})liss, Clem- 
son College, S. C. ; and A. B. Cordley, Corvallis, Oreg. Since the fruit 
trees could not be obtained in Washington for spraying, permission 
was obtained of Director Pattei-son, of the Maryland Agricultural 
ExperiuKmt StJition at (College l^irk, to use trees upon the experimental 
farm. The spraying and taking of notes was done liy Mr. Smith, of 
( the Bureau of Chemistry, and Mr. Symons, of the ?.laryland station. 

PREPARATION OF SAMPLES. 

As in the previous year's work, a large keg of as tine Paris Creen as 
it was possible to olitain was purchased and sulijected to a chemical 
examination. It was found that 2.84 per cent of soluble arsenious oxid 
was pr(\sent, accoixling to th(^ ten-day water-extraction nu^thod. Defi- 
nite quantities of chemically i)ure arsenious oxid were added and four 



12 PARIS GREEN SPRAYING EXPERIMENTS. 

sets of 6 samples each of Paris Greens were obtained and sent to all 
the collaborators. Each sample weiohed 1 ounce and contained the 
following amounts of soluble arsenious oxid: 

Per cent. 

No. 1 : 2.84 • 

No. 2 4.00 

No. 3 5.00 

No. 4 6.00 

No. 5 - 7. 00 

No. 6 - S.OO 

DIRECTIONS FOR SPRAYING. 

(1) Treat each of the samples with 9.5 gallons of watei- (approxi- 
mately 1 pound to 150 gallons) and spray hardy trees such as apples 
and pears. 

(2) Treat each of the <> samples with 9.5 gallons of water and 2 
ounces of previously shiked lime, and again spray hardy trees such as 
apples and pears. 

(3) Treat each of the tl samples with 15.5 gallons of water" (approxi- 
mately 1 pound to 250 gallons) and spray delicate trees such as ])eaches 
and plums. 

(4) Treat each of the samples with 15.5 gallons of water and 2 
ounces of previousl}' slaked lime, and again spmy delicate trees such 
as peaches and plums. 

Make duplicate iuid ti-iplicate experiments in each case if enough 
trees are availa])l(\ AMien possil)le tell what varieties of trees were 
sprayed. 

Carefully note the date of spraying and observe the trees for at 
least three weeks. Also note whether the leaves fall from these trees 
earlier in the fall than from similar trees that were not sprayed. 
Keep a record of the weather conditions during the experiment. 

Always use the whole of the l-omice samph^ forwarded to you with 
the required amount of water. This precaution is of the greatest 
importance, because of the fact that these 1 -ounce samph^s are prepared 
from Paris (Treen to which is added definite amounts of pure arsenious 
oxid in order to obtain the various perccmtages of this substance. 
These are mixed as thoroughly as possible, but sudi mixing can never 
be perfect. Therefore, if only a ytfivt of the sample were used a 
higher or lower percentage of arsenious oxid might be present in that | 
part than in the whole sample. 

REPORT FROM THE MARYLAND STATION, COLLEGE PARK. 

By B. H. Smith, T. B. Symoxs, and .T. K. Haywood. 

Forty-eight trees were utilized for this experiment, two for each of 
the solutions tested, one with and one without the addition of lime. 
The apple trees were York Imperiids; the pears, Keiti'ers; the plums, 



OBSEKVATlOJ^iS, COLLEGE I'AKK, MD. 



13 



American, and the jH'uches, Elbcrtu and Mountain Rose. They were 
all in oood condition and from 5 to U) years old. 

I'he following table gives a description of the weather conditions 
during the experiment: 

Meteorological conditions at College Park, Md. 



Date. 


Precipita- 
tion. 


General character 
of the day. 


Date. 
1902. 


Precipita- 
tion. 

Inches. 


General character 
of the day. 


1902. 


Inches. 




May 11 


0.00 


Partly cloudy. 


May 26 


0.00 


Partly cloudy. 


12 


.00 


Clear-. 


27 


1.53 


Do. i 


13 


.00 


Do. 


2.S 


Trace. 


Do. 


It 


.00 


Do. 


29 


.00 


Do. 


16 
16 


.00 
.00 


Do. 
Do. 


30 
31 


1 ••^' 


Do. 


17 


.00 


Do. 


June 1 


.00 


Do. 


1,S 


.00 


Do. 


2 


.00 


(;iear. 


19 


.00 


Do. 


3 


.00 


Do. 


20 


.00 


Do. 


■1 


.00 


Do. 


21 


.00 


Do. 


5 


.00 


I'artly cloudy. 


22 
23 
21 


.00 

1 - 


I'artly cloudy. 
Do. 


6 
7 
8 


1.07 
.00 


Do. 
Do. 


25 


.00 


Do. 


S) 


.00 


Do. 



OBSERVATIONS. 

The spraying was done on May 11, r.i<>.'>. and the first <)])servation 
was nuide on May IS, no ruin inning fallen in the meantime. No 
injurious effect from the spi'ays could Ik^ discovered on any of the 
trees. The orchard was examined a second time on May 2ti, a light 
rain luiving fallen on May 24. Among th(^ apple trees a small per- 
centage of the leaves of Nos. 4, 5, ;ind 6 (♦>, T, and S per cent of arseni- 
ous oxid, without lime) were very slightly burned, while No. 5 (7 per 
cent of arsenious oxid, with lime) had an occasional blackened leaf. 
The remainder showed no injury. 

A nuuibcr of the pear trees were affected with leaf spot {Septoria 
piji'/co/d) and the pear leaf blister mite {Plnjioptax puricohi) so that a 
great many leaves were begiiniing to blacken and wither. 

A small part of the foliage of all tin' peach trc(\s used in the experi- 
ment had lu^gun to turn yellow and an occasional leaf showed bla(;k 
spots, but the general effect at tiiis tinu? was so slight that no appre- 
ciable ditference could be said to exist betweiMi the se\-eral ti'ees. 

The plum trees showed no injurious etfect from the spraying, with 
the exception of No. 5 (7 i)er cent of arsenious oxid. without lime), on 
which a fi'W lea\ cs were spotted. 

On .lune !t. after three more rains, the ap])le tn-cshail undergone 
practically no change sinci^, the first obsi'r\ ation. 

On the [)ears the disease and mite before mentioned were winking 



14 I'AKIS OKKKN SI'KAYINC! KX I'KKIMKNTS. 

havoc, and a.s Ux' injury was a.s great on the trees spi-ayed with the 
vvcak(!r a,s with the stronj^cr solutions and several trees not sprayed at 
all were atteetcd to m'arly as great an ext(Mjt as those sprayed, it was 
thought best to exclude the pear trees from the exi)erinient. 

Thii [)eachcs wer<i now considerahly damaged, though how nuich of 
this was due to the rather di-y weathei' of the previous moiilli, which 
doubtless had a certain amount of inlluence, was difficult to determine. 
The notes tak(;n at this time ai'e giviMi bcdow: 

I'kaciiks (wiTMonT mimic). 

No. I. A few IcavcM have black HjyotH; alxmt .'55 ju-r cciit tuniiiig yisl'ow and 
(IroppiiiK. 

No. 2. Same. 

No. .'5. A I Kill t T) \H'r r(!iit of Icjivcs more or less Hcorclicil; hall' I lie leaves droiipiii^. 

No. 1. Same. 

No. 5. Alioiit III |M r ceiil o| I he IcHvcM aroisconilird; leaven are yellow aii< I a.s many j 
on t\\v. j^romid as on I he trees. 

No. 0. Not burned an Ijadly as the otiiers and fewer leaven dropping'; a very vigor- 
oUH tree. 

I'kacmios ( wrru m.mk). 

No. I. No leaves hnrned; about 5 per cent dropping. 

No. 2. Same, (^xe(;pt that al)ont 10 j)er cent are drop|»ing. 

No. '.\. \'ery few lea\-es burned; leax'es drop])ing considerably. 

No. 4. Injury a litllc more proiiuunced Ihan on No. 8. 

No. 5. I'liKtically the same as No. \. 

No. (). About r> per cent of leaves burneil and dropping; almost th«' same as Nf)S. 4 
and r.. 

At this tinu' the plum lca\('s were perforated (o some (extent by the 
pbmi le:if shot hole I'lingus (S,pfor!(i ccniKliKi)^ but silso showed con- 
sider:il»le injury from the s])rMy. The notes made on this (hite ar(>, as 
follows: 

I'uMH ( wrriioeT i.imk). 

No. 1. Very f(nv k«ven l)nrned. 

2. i'robably 5 percent of leaves l)nrned. 

3. Same as No. 1. 

4. I>arge ])ercentage of leaves bm-iied at edges. 

5. Large peicentage of leaves burned at etlges. 
(). Large pi'rcentage of leaves burned at edges. 

I'm MS (Willi i.imk). 

No. 1. l'\'W leaves sligiitly l)urned; small tree. 

2. No injury. 

'.\. No injury. 

I. I<'ew leases linrned. 

T). I"\'w leaves burned. 

(). I"\'\v leaves burnecL 

After twenty (liiys nnotlief examinnt ion was made. The interven- 
ing wet wt'ather wa^ evidently of great beuelit to the orchard, as the 



CONCJ.I'SIONS, ("OMJKil-: I'AKK, M I >. IT) 

decs li;i<l Im'^uii ;i new j^rowili mihI (he Iciurs, <lc\ ('l(»|)t'(l :i dnikci' 
color. 

'riic sIImIiI itijmy to (lie :ip|)lf I rco of tlir nionlli lict'orc wmsmoI 
Mol i('('!it»l(\ l>olli (liosr s|)I":iv(m1 willi imd willioiit liiiic hciiiL;' in ^dod 
('()ri<lit ion. 

'I'lic |)c;icli('s were jocaicd on :i diy knoll and uccoi'dint^'ly liiid siil" 
i'crcd niosl from tlic didiiL;iit. Itnl :il (his ol)s»'i'\:il ion. MJlcr liMvin^' 
(li'o|)|)rd t lici r ;ill( (led lc;i\cs and piil foi'lli new onrs. hoi li scries of 
(he trees had so I'm' rcciipcr'ulcd as (o show scarcely any clVcc( i'foni 
(he Talis (Ircen. the l'olia»:;"(' Ix'inn" nearly as (irnd^ as upon unsprayed 
(I'ces. 

'I'lie |)liiMi (rees, while showini;' more injury than the peaches, were, 
decidedly ini|)ro\ cd. 

The last cxaniiiiatioii was made on .\iil;-iis( S, and as Tar as could lie 
ascertained (he (i-eesof all \arie(ics had coinple(ely I'ecoN'crcd I'roni 
the cH'ccts of the vtu'ious sprays. 

CONCLUSIONS. 

The e(|'ec( of (licscr I'lU'Js (ireens, l>o(li wi(h and w itli()u( lime, upon 
the apple (reos was vei-y slight, iuul, as fai' as could Ix^ estimated, the 
same ma\' he said of (he pears. 

To t he peach t riu'sconsidei'ahlc tem|)orary in jui'v, asslH)wn l)y a drop- 
piti<4 of the leaA'cs, was done l»\ all the wiecns wi(h()u( lime, al(lioue-|i 
(he ( rees seemed (o !-eco\ cr later in (he season. \\ i( h lime (he peaches 
were no( injured (o an\ i^i'cal e\(ent. e\ en tem|)orarily . \y\ i^i'eens 
Nos. I, i', and ;'. (•^..sl. I. and .'> per cent of arsenious oxid ), hut were, 
injured (enipoiaril\' lo (pii(e an e.\(ent l»\ i^i'ecns Nos. I, .">. and <» ((I, 
7, and S per cent of arseidous oxid). All of t he (rees, however, seemed 
to iccovcr helore the end of the season. An interesting;" point not«'(l 
in the case of the peach t rees was (ha( noinjuiv was iio( icea hie uu( il a 
month af(er the a|)plicat ion of (he spray, the d(day in action heine- 
prol)ali|y due (o th(^ ahseiice of I'ain. 

Anodier fact emphasi/ed l>y ( he ol)sef\ai ions was tlia( the injury 
alwa\s dcpcnijcd to a consideraltle e\(en( upon the phvsi<'al condition 
of (he indi\idual tree; in a numher of cases a particularly vij^^orous 
ypecimen showine' no injury, while its less (liri f(y nei^hhor, which 
was perhaps spiayed wi(li a Paris (ireeu con(aininL' h'>s soluble 
arsenious oxid, was seri(»usly daiuae('<l. 

1 P'loni the results of (his work i( is Ixdicvcd that a|»ple and |»rohal)ly 
pear dees can he sprayed wi(h Tar'is (Jieen containing- S per centof 

] .s()lid)le arsenious o.xid and sustain no injury. The ol)ser\ a( ions made 
on peach and plum t rees (end (o >li(t\\ (hat if lime is added i'ai'is ( Jreen 

I coiitainim;- as hi^^li as Ti per cent of (n-i- arseidous oxid may he safely 

r U«ed. 



16 



PARIS GREEN SPRAYING EXPERIMENTS. 



REPORT FROM THE NEW YORK STATION, ITHACA. 

By John Craig and H. E. Weed. 

The Paris Green was applied to the foliage of apple, pear, peach, 
and plum trees according to the directions accompanying the .samples. 
The trees were sprayed on May 25, and 26, 1903, and the final results 
observed and notes taken on June 16. In the notes on the damage 
done to the foliage given below the terms "no injury indicated," 
"injury indicated," ".somewhat injured," "injured," and "badly 
injured" are used to indicate the various degrees of injury in order 
that the results may l)e compared. In the same way the terms " spray- 
ing safe," "spraying questipnal)le,'' and "spraying unsafe" are 
employed to indicate whether or not it would be expedient to spray 
with the amount of soluble arsenious oxid contained in the solution. 

The rainfall during the period of the experiment and the results 
obtained are as follows: 

Rainfall at Ithaca, N. Y. 



Date. 


Precipi- 
tation. 


Date. 


Precipi- 
tation. 


Date. 


Precipi- 
tation. 


Date. 


Precipi- 
tation. 


1903. 


Inches. 


1903. 


Inches. 


1903. 


Inches. 


1903. 


Inches. 


May 1 


T. 


May 15 


.00 


May 29 


.01 


June 12 


1.66 


2 





16 


.00 


30 


.00 


13 


.01 


3 


.08 


17 


.00 


31 


.00 


14 


.01 


i 


.13 


IS 


.00 


June 1 


.00 


15 


.11 


6 





19 


T. 


2 


.00 


16 


T. 


6 





•20 


.00 


3 


.00 


17 


.19 


7 


T. 


21 


.02 


4 


.00 


■18 


.28 


8 





22 


T. 


5 


.00 


19 


.09 


9 





23 


.00 


6 


.00 


20 


1.06 


10 





24 


T. 


7 


.03 


21 


.74 


11 





25 


.00 


S 


.01 


22 





12 





26 


T. 


9 


.05 


23 


.54 


13 





27 


T. 


10 


.02 






14 





28 


.06 


11 


.04 







OBSERVATIONS. 

APPLE, VARIETY GOLDEN SWEET. 



Mixture used. 



Effect on foliage. 



Remarks. 



fWithout lime 
jWith lime... 

I Without lime 
IWith lime... 

(Without lime 
[With lime ... 

[Without lime 
(With lime ... 

(Without lime 
I With lime... 

(Witliout lime 
|with lime . . . 



Injury iudicateil . . . 
No injury indicated 

Injury indicated ... 
No injury indicated 

Somewhat injured. . 
Injury indicated ... 

Injured 

Slight injury 

Injured 

Somewhat injured . . 

Badly injured 

Injured 



Spraying safe. 
Do. 

Do. 

Do. 

Spraying questionable 
Spraying safe. 

Spraying unsafe. 
Spraying .safe. 

Spraying unsafe. 
Spraying questionable. 

Spraying un.safe. 
Do. 



Bui. 82, Bureau of Chemistry, U. S. D<,-pt. Agr. 



Plate I. 





Bui. 82, Bureau of Chemistry, U. S. Dept. Agr, 



Plate II. 





OBSERVATIONS, ITHACA, N. Y. 

()li.s(rr<illon.'< — ('ontimK'd. 
I'KAK, VAKIKTY BAKTLETT. 



17 



Mixture used. 



I Without lime. 
Witli liiiu' 



(Willioiit linio. 
With liiiie 



[Without lime 
With lime ... 



[Without linu-. 
Willi liiiK' 



jWilhout liiiu' 
Iwith lime . .. 



[Without lime, 
jwith lime.... 



[Without lime. 
jWith lime .... 

(Without lime. 
With lime.... 



Without lime. 
With lime 



Without lime. 
With Umv .... 



Without lime. 
With lime 



[Without lime. 
[With lime 



Effect ou foliage. 



lujury iudieateil 

No injury iu<licated . 

Souiewhiit injured. .. 
lujury indicated 

Injured 

injury indicated 

Tnjureii 

Somewlmt injured. .. 

Ha<ily injureil 

Injured 

Kadly injured 

Injured 



Remarks. 



Spraying safe. 
Do. 

Spraying <nie.stionabIe. 
Si)raying safe. 

Spraying unsafe. 
Spraying .safe. 

Spraying unsafe. 
Si)raying fjueslionable. 

Spraying unsafe. 
Do. 

Do. 
Do. 



PLUM, VAKIEIY MARIANNA. 



Spraying safe. 
Do. 

Si>raying (lucstionablc. 
Spraying .safe. 

Si)rayiug unsafe. 
Spraying .safe. 

Spraying un.safe. 
Somewhat injured , Spraying questionable. 

Badly injured | Spraying uusafe. 

Injured Do. 



Injury iudicMtiMl 

No injury indicated . 

Injured 

Injury indicated 

Injured 

Injury indicated . ... 

Badly injured 



Badly injured 
Injured 



Do. 
Do. 



[Without lime. 



PEACH, VARIETY, STUMP. 



fWithout lime | Scmu^wliat injured Spraying questionable. 

[With lime Injury indicated ! Spraying .safe. 

[Without lime Injured Spraying unsafe. 

jwith linu' ' Injury indicated Spraying .safe. 

[Without lime ! Injured Spraying unsafe. 

(With lime Somewhat injured Spraying <|uestionable. 



Badly injured Spraying unsafe. 



I With lime Injured. 



[(Without lime | Badly injured . 

jlWith lime ! Injured 

[Without lime ! Badly injured . 



[With lime Injured. 



Do. 

Do. 
Do. 

Do. 
Do. 



25214— No. 82—0.1 



18 PARIS (IKEEN SPRAYING EXPERIMENTS. 

On June KJ and 17 another set of .spraying's was made on the plum 
trees, the object being to obtain the cunudative effect of the spra3^s 
and also to ascertain whether the same injury would be done at this 
time as was noted after the sprayings of May 25 and 26. In this 
experiment the plum trees previously used were again sprayed with 
the same solutions and, in addition, some trees not used before were 
treated. Solutions Nos. 1, 2, and 3 were applied on the afternoon of 
June 16, and solutions Nos. 1, 5, and 6 on June 17. A rainfall of 0.19 
inch occurred, however, on the same day, and the results with Nos. 1, 
5, and 6 were entirely inconclusive, as no effect at all was produced, 
except on protected portions of the lower leaves. 

The results obtained with Nos. 1, 2, and 3, applied on June 16 and 
followed by 0,19 inch of rain on the following- day, w^hile not definite 
enough for ta))ulation, plainly indicate that the last spraying did more 
injury than the first, and this was especially noted in the case of the 
trees which received two applications. The greater amount of injury 
resulting from the second spraying can ))e easily explained, as at the 
time of the first spraying the leaves were still 3"oung and the weathei* 
for four weeks previous had been extremel}^ dr}'. Furthermore, from 
the w^eather chart it will be seen that only a small amount of rain fi^ll 
during the three weeks following the spraying on May 25 and 26. 

CONCLUSIONS. 

The results obtained may be sinnmarized as follows: 

(1) Of the apple, pear, })lum, and peach foliages the apple is injured 
the least, the pear and plum are affected to about the same degree, and 
the peach is injured the most. 

(2) If only one application is made, Paris Green containing 1 per 
cent of free arsenious oxid can be applied with safety to apple trees 
and with the addition of lime 6 per cent may be })resent. 

(3) If only one application is made to pear or plum trees, Paris 
Green containing 3 per cent of free arsenious oxid can be applied with 
safet}^ and with the addition of lime 5 per cent. 

(4) One application to peach trees of Paris Green containing 3 per 
cent of free arsenious oxid can not be made with safety without the 
addition of lime; with lime 1 per cent ma}^ be used. 

(5) Two applications will do more damage than a sing^le one, and 
more injury is apt to occur if the weather conditions were normal 
previous to the spraying than if very dry weather obtained. 

Some observations were made on the manner in which the foliage 
of the different trees is affected. On the apple tree the injury is indi- 
cated by small, light-brown spots, well distributed over the leaves. 
On the pear and jjlum trees the damage is indicated by larg-er dark- 



OBSERVATIONS, KINGSTON, R. I. 



19 



l)r()\vn s[K)ts, occufi-iii^- mostly uloiio- the sides of the leav'cs, while on 
llie peiicli leiiA'es tlie s[)ots are hiroc, nearly circular, and distributed 
ov(M" various portions of the lea\es. 

REPORT FROM THE RHODE ISLAND STATION. KINGSTON. 

By F. W. (.'akduikI A. K. Stkxk. 

The sprayino- mixtures were made u\) strictly accordinj^ to din^c- 
tions. The aj)pie and pear trees were sprayed on Ahiv 25, 1 !»<);',, and 
the peaches on May 2". The foUowini;- table shows the weather con- 
ditions under which the e\])eriment was con(Uu'ted: 

Mctcor<d()</icfi/ (Idid, Kiiir/Klon, R. I. 



Date. 


Rain full. 


Character of day. 


Date. 
1903. 


Rainfall. 


Character of day. 


1903. 


Inrhcst. 




Iiichcu. 




May -jr, 


0.(N) 


Ckvir. 


June T) 


0. 00 


Smoky. 


20 


.00 


Do. 


(> 


.IH) 


Do. 


27 


.00 


I'aiily cloudy. 


7 


.41 


Cloudy. 


28 


.00 


Cloudy. 


8 


.86 


Do. 


29 


.00 


Clear. 


y 


.00 


Do. 


30 


..')0 


Partly cloudy. 


10 


. 39 


Do. 


31 


.00 


Clear. 


11 


1.77 


D<i. 


.Tuiiu 1 


.00 


Do. 


12 


Ar> 


Do. 


2 


.00 


Do. 


Vi 


.00 


Clear. 


3 


.00 


Do. 


14 


.(H) 


Do. 


■1 


.00 


Smoky. 









OBSER,VATIONS. 



Al'l'LES. 



I The a])ple trees usihI for the e.xperiment wei'e Northern Sjn's, and one 
1 tree was sprayed with each sam[)le of <ireen. The trees stood in two 
( row«, side by side, and the samples with lime were applied to one I'ow 
; and those without lime to the other. These experiments i>ave but 
slight results. Of the trees sprayed Avithout lime the two receiving- 
samples Nos. '2 and .'> (4 and 7 per cent of arsenious oxid) showed .some 
burnino- of the folia^'e after the rains of June 7 to 10. The tree 
sprtiyed with No. '2 seemed to be the most atlected. The trees sprayed 
j with the addition of lime sufl'ered no appreciable burning- of the 
foliage. 

Pi:ak>. 

The pear trees receiving no lime wm-e the Frederick Clapp, Hardy, 
'• Kiefter, Pitniaston Duchess, Supei'tine, and Anjou; tho.se receiving the 
^ addition of lime were the Hardy, Hoosic, Louise Bonne, Sheldon, and 



20 PAEIS GREEN SPRAYING EXPERIMENTS. 

Urban iste. These trees were all in a single row and every other one 
was sprayed with the samples containing no lime, the alternates being 
sprayed with the admixture of lime. After the rain of June 7 to 10 
the Pitmaston Duchess, sprayed without the addition of lime, had a 
few burned leaves, and the Kieffer and Hardy, similarly treated, 
showed slight traces of burning. The trees receiving the spraying- 
mixture mixed with lime showed no trace of burning whatever. 

Peaches. 

The peaches sprayed stood in two rows, side by side, one row receiv- 
ing the Paris Green alone and the corres])oiiding trees in the other row 
receiving the same green with the addition of lime. Those receiving 
the samples with lime were three of the Crawford Late variety and 
three Fitzgeralds. Three Champions and three of the Hill Chili vari- 
ety were sprayed with the samples without lime. None of the trees 
showed any effects of the spraying until after the rain of May ;5o. The 
results in every case were proportionate to the amount of soluble 
arsenious oxid used. Those receiving the lime were far less afl'ected 
than those not receiving it; in fact, the former showed hardly an}'^ 
effects until after the heavy rains of June 7 to 10. The tree which was 
spra3'ed with sample No. 6 (8 per cent of arsenious oxid), without lime, 
lost nearly all of its leaves and did not recover during the season. A 
number of the branches died and it made practicalh' no growth after 
the application of the green. The tree sprayed with the same sample 
with lime was affected about the same as the tree sprayed w ith sample 
No. 1 (2.81: per cent of arsenious oxid) w itliout lime. As ))efore stated, 
the other trees were afl'ected proportionately to the amount of soluble 
arsenious oxid in the sample with which they were sprayed. 

It appears that sample No. 3 (5 per cent of arsenious oxid) repre- 
sents the maxinnun limit when lime is added, since Nos. 4, .5, and (6, 
7, and 8 per cent of arsenious oxid) caused confide ial)le damage. All 
of the greens did too nuich injury to the peac-h trees when used with- 
out lime. In no case did the trees spi-ayed seem to lose their leaves 
any earlier than those not sprayed. 

The illustrations accompanying this report show the injury to peach 
trees inflicted by several of the greens, and >vith their legends explain 
themselves. 

REPORT FROM THE SOUTH CAROLINA STATION, CLEMSON 

COLLEGE. 

By C. E. Chamisliss. 

The solutions were made up and applied in strict conformity to the 
accompanying directions. The table following shows the condition of 
the weather during the time of the experiment. 



OBSERVATIONS, CLEMSON COLLEGE, S. C. 

Meteorological, data, Clrmnon College, S. C. 



21 



Date. 


Riiiiifiill. 


Miiximiim 

tcmpiTa- 

ture. 


Minimmii 
lempeni- 

tiire. 


Dato. 
1903. 


Uainfall. 


Maximuin 
tempera- 
ture. 


Minimum 
tempera- 
ture. 


1903. 


Tnclien. 


op 


op 


Tnrhcx. 


°F. 


°F. 


.iiuir rj 


00 


75 


58 


.Itine 22 


T. 


89 


69 


in 


00 


71 


■12 


23 


00 


92 


61 


11 


00 


80 


•17 


24 


00 


89 


56 


1.^) 


00 


H9 


54 


25 


.08 


90 


60 


](! 


00 


89 


54 


20 


.09 


80 


GO 


17 


00 


88 


50 


27 


.10 


80 


66 


is 


00 


91 


58 


28 


00 


85 


62 


1>.» 


00 


91 


f)0 


29 


00 


87 


66 


•20 


00 


91 


(i2 


30 


00 


93 


62 


■21 


00 



















OBSERVATIONS. 

AlMM.KS (\\ITII()i:'l' I.IMk). 

This group of tro(\s was s[)i-!iyt'(l on Jiiiu* IT), 1908, and ob.sorvations 
wero iiiado on Jun(> ^1?^ up to which time no i-aiu liad t'aUen, and ao-ain 
on July 11, during' which jXM'iod (hci'c^ had hocn several rainfalls. At 
tho first observation no cth'cts were notii-eahle on any of the trees. 
At the second observation the following eii'ects wert^ noted: 

No. 1. Shmnons Red. — The edgew of some leaves were black and many liad fallen. 

No. 2. Maverick Smeet and Laurence (Ireen'mg. — Foliajire of the former was hlaek on 
the edges, but no leaves had fallen. About one-fifth of the foliage of the latter was 
black on the edges, but no leaves had fallen. 

No. 3. Laurence Greeuiug and Elgin Pij>piv. — The foliage of the former was hadlj' 
burned and one-third of it had fallen; one-third of the foliage; of the latter was burned 
very slightly. 

No. .'/■ Mr-^. Jirt/an and Shocklei/. — The foliage of the f()rmer was only slightly hurned 
anil a few leaves had falKn; the foliageof the latter was burned and t lie tree seemed 
to be sickly. 

No. ,5. Yoppn Favorite and Golden Beauty. — One-half of the foliage of l)oth had 
fallen and the rest was badly burne<l. 

No. 6. Horn. — One tree suffered a slight hnrning of the foliage, whih- the other was 
practically unaffected. 

Apples (with lime). 

This group of trees was sprayed on flune !♦], 1903, and observations 
were made on the dates mentioned a})Ove. At the first o])ser\ ation no 
etfect was noticeable, Init at the second the following changes were 
noted: 

No. 1. Black Warrior. — One-lialf of the foliage had fallen and the remainder was 
slightly burned. 

No. 2. Ilawh Janet. — Only a few leavi'S had fallen, the remainder heing slightly 
hurned. 

N^o. 3. (jrime.'i Golden. — These two trees were apparently not affected. 

A'o. 4- Faniilij and lUiodeii Orange. — A few Icaxcs had fallen. 



22 PARIS GREEN SPRAYING EXPERIMENTS. 

No. ■'). Red June. — One-thinl of tlie foliajje liad fallcii and the remainder was 
•burned. 

No. C). Jeivetts Bei^t and ClutlUdiooclwe. — One-fifth of .the foliage of the former liad 
fallen and the remainder was burned. The foliage of the latter was only slightly 
burned. • 

Pe.xches (wiTnorx lime). 

These trees were spra^^ed and o))Hervations taken on the dates men- 
tioned al)ove for apples without lime. 

No. 1. Tinlei/'s October. — At the first observation a few leaves had fallen and at 
the second four-fifths of the foliage had fallen and the remaining leaves were badly 
burned. 

No. 2. Tinlcy' a October. — At the first observation a few leaves had fallen and at 
the second four-fifths of the foliage had fallen and the remaining leaves were badly 
burned, but new leaves were putting forth. 

Peaches (with lime). 

These trees were spra3'ed on June 16, 1903, and observations were 
taken on the dates mentioned above. 

No. 1. Klbertd and Stump the iroj7(/.— At the first observation a few leaves had 
fallen from both. At the second observation the former had lost one-haH of its foli- 
age and the remainder was badly burned, while the latter had lost fmir-fifths of its 
foliage, the remainder being the terminals. 

No. 2. T'mlei/ if October. — At the first observation a few leaves had fallen. At the 
second observation four-fifths of the foliage had fallen, but new leaves were imtting 
forth. 

The stronger spraying solutions, Nos. 3 to (i, were not tested on 
the peach trees. 

Plums (without lime). 

The trees were sprayed on June 15, and observations taken on the 
dates mentioned above. 

No. 3. Lombard. — At the first observation a few leaves were slightly burned. At 
the second observation one-third of the foliage had fallen. The leaves were badly 
burned on one tree and very yellow on the other. New leaves were putting forth. 

No. 4. Chalco. — At the first observation the leaves fell readily when the tree was 
shaken. At the second observation only a few leaves remained on the trees. 

No. 5. Ogon and Wannmaker. At the first observation yellow leaves were numerous 
and fell readily when the trees' were shaken. At the second observation all of the 
leaves had fallen. 

No. 6. German Prune and Juicij. — At the first observation no effect was noticeable. 
At the second both were badly burned, but practically no leaves had fallen. 

Plums (without lime). 

The trees were sprayed on June IH. 1903, and observations taken on 
the dates mentioned al)ove. 

No. 3. Shiro and Fellenburg.— At the first observation no effect was noticeable. At 
the second some of the foliage of the former had fallen an<l yellow and ba<lly burned 
leaves were present. Only a few leaves of the latter tree had fallen, but they were 
badly burned. 



OBSERVATIONS, DURHAM, N. H. 28 

No. 4- Red Jim e. — At the first ol)servati()ii leaves fell when the tree was sliaken. 
At tiie second nine-tenths of tlie folia^'e hail fallen and the reniainin<j: leaves were 
iiadly ])nrned. 

Xo. fi. WIcksiDi (1)1(1 Alunxldnrc. — At the first <il)servation tlic lca\fs of the fdrnier 
tree fell readily wheTi shaken, aii<l burned Icuvi's were innuerous on the latter. At 
till' second olist'rvation one-half of the foliage of both had fallen, hnt new leaves 
were ])nttin<; forth. 

A'o. /:. ]Vick:'ion <i)kI tSiillan. — At the first observation leaves fell when the trees were 
shaken. .\t the second one-third of the folia<je had fallen, but new leaves were put- 
tin<i; forth. 

RESULTS. 

These results, ol)tained as they were by one spraying- of one or two 
trees by each sample, are not considered conclusive; a tabulation of 
the results of several sprayings would ])e more significant. However, 
from the results olitained it would appear that it is not safe to spray 
apple trees with Paris (Ireen containing- niore than 4 pe^' cent of solu- 
h\c arsenious oxid without lime; with lime not more than f> per cent 
should 1)6 present. None of the samples, either with or without lime, 
appears to be safe on })ea('ii foliage. The smallest percentage used on 
plum trees was T) ])er cent of solul)l(> arsenious oxid, and that was too 
strong without lim(\ but from the results obtained with 5 per cent of 
solu])le arsenious oxid with lime, it would seem that 4 per cent with 
lim(> would l)e safe. 

REPORT FROM THE NEW HAMPSHIRE STATION. DURHAM. 

By C. M. Weed and .1. L. Randai.i.. 

Plum and apple trees were used for this experiment, as they were 
the only ones availaltle for the purpose at the time. All the trees 
were of thrifty growth, the apples of tive 3'ears bearing and the plums 
of two j^ears. They were all of the same ag"e and practically the same 
height. The trees were sprayed on July 28, which was warm and 
clear, and the effect on the foliaj^e, wheneverthere wa.s any, was noted 
within less than twenty-four hours. The following notes were taken: 

OBSERVATIONS. 

AiM'LEs (without lime). 

Baldwin apples were used exclusively both for the experiments with 
and without Iim(>. 

No. 1 showed several burnt spots, but was not severely injured and no leaves fell. 

No. 2 did not differ from No. 1 and tlie spots were not very abundant. 

No. .'), although there seemed to be no cause for it, was burned more than any 
other tree excei)t No. 6. Brown blotches apj)eared on a large jiart of the foliage and 
a few leaves curled as if al)out to fall. 

Nos. 4 and 5 ])oth had many burned spots and some blotches. None of the leaves 
curled, except occasionally when a blotch or spot came to the edge of the leaf. 



24 PARIS GREEN SPRAYING EXPERIMENTS. 

No. 6 was injured the most of any. Large patches appeared on many of the leaves, 
which turned brown. Under the microscope the cell protoplasm was shrunken in 
these blotches and in the centers of the smaller spots. 

Apples (with lime). 

No. 1 had small brown spots on a very few leaves. 

No. 2 was burned more than No. 1, yet the leaves did not fall and the cells were 
killed only in a few places. 

No. 3 suffered little, if any, more injury than No. 2. 

Nos. 4 and 5 showed some burned spots on the leaves unevenly distril)uted. These 
trees were affected about the same as Nos. 1 and 2 without lime. 

No. 6 showed smaller but more numerous spots than those observed on Nos. 4 
and 5. 

Plums (without lime). 

No. 1. Imperial Sage. — The leaves showed (luite prominent l)rown spots, which 
were more numerous in the direct sunlight than on shaded parts of the tree. 

No. 2. Bradshaw. — This tree was slightly more damaged than No. 1, but none of 
the leaves was injured enough \o fall. 

No. .?. Abnndance. — This tree was damaged more tlian any other except No. 6. 
Many of the leaves were curled and a few fell. The tret^ had not entirely recovered 
when the leaves fell in the autumn. 

No. 4. W(tiihbuiloi). — Some of the leaves were burned and curled, but the injury 
done was not so great as in the case of No. 8. The tree had recovered l>efoj-e the 
leaves fell. 

No. .'J. Ydlow Japan. — A few leaves curled and fell. Tliis tre(> was burned more 
than No. 4 and about the same as No. 3. 

No. a. Wy<mi. — This tree was burned more than any other. Man3^ of the leaves 
at the top were half burned and a large number fell. 

Plums (with lime). 

No. 1. De Solo. — On July 30 this tree showed only a few scattered brown spots on 
the leaves. On August Ih it had entirely recovered. 

No. 2. German Prune. — The injury was about the same as that inflicted on No. 1, 
without lime. A few brown spots were observed, which gradually disappeared, until 
on August 21 the tree had entirely recovered. 

No. 3. Rehie Claude. — About as much damage was done in this case as to No. 2, 
without lime, the lime seeming to nullify the effect of about 1 per cent of soluljle 
arsenious oxid. On August 25 the tree had entirely recovered. 

No. 4- Green Gage. — The leaves of this tree were burned in round spots, and a few 
curled; but in thirty days it had entirely recovered. 

No. 5. Satsuma. — This tree was damaged about the same as No. 4, without lime. 

No. 6. Weaver. — Spots and blotches apjieared, and a few leaves fell; but the tree 
recovered before the season was over. 

The authors of the report from the New Hampshire station prefer 
not to give an opinion in regard to the amount of sohible ar.senious 
oxid that can be endured by api:)le and phim trees, as the data o})tained 
is deemed by them insufficient to serve as a basis of such an opinion. 
It appears, however, to the author that certain tentative conclusions 
may be drawn which can be compared with the results o})tained ]»y the 
various other stations and definite conclusions thus be obtained. Bas- 



OBSERVATIONS, CORVALLIS, OREO. 25 

ino-, thou, ail ()])iiii()M upon this single set ot" cxpcriiiKuits, it would 
a[)p<'iii-: 

(1) 'I'hal when liiuc is not used a l*ai-is (Ji'ccn coiitaiiiiiii^- I per- cont 
of sohi)>l«MU's('iiious oxid can l»c used (jn ap])l(' trocs, while one ron- 
tainino- 7 pei' cent can he used with the addition of lime. 

(2) That it" lime is not used a Pai'is (Jieen containino- 4 \h'v cent of 
,solu])lo arsenious oxid can he used on plum trees. If lime is used it 
would appeal' that a J'aris (Tre«Mi containiiij»' 5 or <> per cent mi»»ht )»e 
safcdy used. 

REPORT FROM THE OREGON STATION, CORVALLIS. 

By C 11 ('()Ri)i,KY. 

Ill th(^ experimental work don(> in t(\stino- the (dfects of varyino- 
amounts of free arsenious oxid in l*aris (JrecMi on foliage, the dii-ec- 
tions were very carefully followed. Forinich (est the re(iuired amount 
of water was placed in a Itarrel, to which wasadd(Kl the amount of milk 
of lime specitied, if any. and then the Paris drreen. The whole was 
stirred thorouo-hly and at once spraycnl ujxxi tho trees. The work was 
done with a small hand pum}). titt(>d with a Vermoi'cl nozzle, and o-reat 
care was exercisetl to see that every leaf was thoroughly sprayed. In 
addition to the work outlined the eti'ect of the stroiii>er sprays (1 ounce 
to tt.r> oallons) on the foliage of a few' delicate plants was tested. 

riie sprays without the addition of lime were appli(^d on July 10, 
VM)?>. Evaporation was so rapid that the foliage was dry a few 
moments after being sprayed. On July 11 the conditions were similar, 
and samples Nos. 1 to 3, with 15.5 gallons of watei' and '2 ounces of 
lime, were applied. The remainder of the samples of that set, Nos. 
■i to 0, with 15.5 gallons of water and 2 ounc<\s of lim(^, and Nos. 1 to 6, 
with 9.5 gallons of water and 2 ounces of lime, wcM'e applied on rluly 17. 

In the meantime, i. e., from July lo to -Fuly 17, tlie weather had 
remaiiKHl clear and bright. A critical examination, made on the latter 
date, of the trees sprayed on fluly !<> and 1 1 showed that none of them 
was injured. 

On July 21 and 23 there were slight show'ers, and (doudy w(»ather 
continued throughout the week. Thorough exaiiiiiiations were made 
on fful}" 23, August 3, and Decemlier 1,'the r(\sults of which are given 
in the tabular statements which follow. A table is also given show- 
ing the meteorological conditions which obtained for a number of 
days following the application of the sprays. 



26 



PARIS GREEN SPRAYING EXPERIMENTS. 

Miti'iiriilnt/iraJ riirtditi(m>f nl < hrrdllix, Orr;/. 



Date. 


Tempera- 
ture. 


Pre- 

eipitu- 

tion. 


Charaeter of 
day. 


Dale. 


Tempera- 
ture. 


Pre- 
cipita- 
tion. 


Character of 
(lay. 


1 Max. 


Min. 


Max. 


Min. 


1903. 
July 10 
11 
12 
13 
14 
l."i 
If) 
17 

IS 

lit 
20 


°F. 

86 
70 

74 
70 
77 
86 
81 
82 
7^ 
81 
86 


°F. 

48 . 

51 

47 

.52 

47 

48 

.tO 

47 

48 

.50 

50 


Tuch. 

0.00 
.00 
.00 
.00 
.00 
.00 
.00 
.00 
.00 
.00 
.00 


Clear. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 


1903. 
July 21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 


°F. 
70 

72 
66 

74 
75 

77 
S» 
84 

77 
75 
77 


°F. 
50 
47 
52 
59 
47 
42 
45 
45 
54 
.55 
46 


Inch. 

0.04 
.00 
.05 
.00 
.00 
.00 
.00 
.00 
.00 
.00 
.00 


Cloudy. 

Do. 

Do. 

Do. 
Partly cloudy. 

Do. 
Clear. 

Do. 
Partly <-loudy. 
Ch'ar. 

Do. 



OBSERVATIONS. 

Table I.— APPLK8 WITHOUT LIME. 
[1 ounce to 9.5 gallon.^.] 



Sam- 
ple 

No. 


Variety. 


Injury. 


July 23. 


August 3. 


December 1. 




fMackintosh 

i Carolina June 


None 






1 


do 


do 


Do 




[xuft's Baldwin 


do 


do 


Do 




fBenoni 


do 


.do 


Do 


2 


Crab 

Spitzenber.a: 

f do 


do 


do 


Completely defoliated. 




do 


do 




do. 


do 




3 


J do 


do 


do 


Do 




Spokane Beauty 


do 


.do 


Do 




1 do 


do 


do 


Do 




1 do 


Few leaves slotted . . . 
None 


No increase of spots .. 


Nearly defoliated. 
Completely defoliated. 




f 


r, 


• Yellow Transparent . . 
Ig rimes' Golden 


do 


do 




do 


do 


Completely defoliated. 
Almost defoliated. 
Half of leaves fallen. 

Few leaves fallen. 
Completely defoliated. 




Hyde's King of West . 
Langford 


Few leaves spotted. . . 
Pew leaves spotted 

and few killed. 
do 


No increase of spots . . 
No increase of injury. 

do 


6 


■i'akama 




Yellow Newton Pip- 
pin. 


do 


do 







OBSERVATIONS, OORVALLTS. OREO. 



27 



Ohsrrviitioiix — ('oiili lined. 
APPLES, WITH LIMK. 



Sani- 


Viiriety. 


Injury. 


1)10 

No. 


July 2:i. 


August 3. 


December 1. 




fRomc Beauty 


None 


None 




1 


1 do 

[ do 


do 

do 


do 


Do 




do 


Half of leaves falU'ii 




do 

Waxen 


<]o 


.. .do 


Completely defoliated. 




do 


do 


2 


do 


do 


do 






f do 


do 


do 


fallen. 
Do. 


3 


1 do 


do 


do 


Do. 




f lio 


do 


do 




4 


do : 


do 


do 


fall en. 
Do. 




do 


do 


do 






( •'" 

do 


do 


do 


fallen. 


5 


do 


do 






1 

f do ; 


do 


do 


fallen. 


ti 


do 


Few leaves slightly 
spotted, mid .-i few 
more killed. 


\o iiuTcjistMif injury. 


fallen. 
Do. 



T.iiii.E ir.— PE.VRS, WITHOUT LIME. 
[I ounee to H.SKalloiis.] 



1 


jDirectenr .Ui)hando.. 


None 


None 


Completely defoliated. 


{colonel Wilder 


do 


do 


But few leaves fallen. 


.> 




do 


<lo 




3 


Bartlett 


do 


do 


Few leaves fallen. 




I 


do 


do 


Do. 


•1 


do 


do 


Do. 






Leaves sli^-liily in- 




•'■> 


rVVinter Uarllett 

[Fani.' 


jured about luar- 
fjins of holes eaten 
by slug.s. 


No increa.se of injury. 


Coinpletely defoliated. 


6 


Gene.sta 


None 


None 


Do. 



PE.\KS, WITH LIME. 



1 












jButTum 


do 


do 


causes. 
Completely defoliated. 
Do. 


3 


1 do 


do 


do.. .. . .. 


■1 


Lincoln 


do 


do 


But few leaves fallen. 


h 




do 


do 


Do. 




f....do 


do 


do 

do 




6 


. 


do 


fallen. 
Completely defoliated. 











28 



PAKIS GREEN SPRAYING EXPERIMENTS. 



Ohsrrrdiions — Continued. 

Table III.— PLUMS," WITHOUT LIME.& 

[I ounce to 9.5 gallons.] 



Sam- 


Variety. 


Injury. 


ple 

No. 


July 23. 


August 3. 


December 1. 


1 






None 


Completolv defoliated. 




r 


do 


do 


Do. 


3 





do 


do 


Do. 




i 


. do 


do 


Do. 




f 


do 


do 


Do. 


4 


{■■: 


do 


do 


Do. 


h 




do 


do 


Do. 


6 




do 


do 


No record. 













oThe.se trees were all prune-bearing plum trees, and were reported under tlie former designation; 
but the term " plnm " is here used to bring them into comparison with the other plum trees used in 
the experiment. 

f'For the report on plums sprayed with the addition of lime see text at close of tables, page 29. 



Table IV.— PEACHES, WITHOUT LIME. 
[1 ounce to 1.5.r) gallons.] 



Sam- 
ple 
No. 




Injury. 




July 23. 


.\ugust 3. 


December 1. 


1 




None 


None 


Three-fourths of leaves 
fallen. 






2 


do 


Slightly injured 


No increase of injury. 








len. 


3 


do 


do 


do 


One-half of leaves fal- 
len. 
] 


4 


do 


Ctmsiderably spotted. 


One-fourth of leaves 








fallen; the rest in- 


I Do. 








jured. 


1 


5 


Mont Rose 


do 


... .do 


Do. 




f....do 


Badly injured 




f; 




fallen; the rest in- 


il 








jured. 






....do 


do 


do 


Do. ' 














PEACHES, WI 


TH LIME. 






Lewis's Seedling 


None 




Three-fourths of leaves 
fallen. 


1 










One- halt of leaves 
fallen. 


One-fourth of leaves 

fallen. j 

Do. ! 

Do. '* 

Do. 1 

Do. ' 

Seven-eighths of leaves | 

fallen. 










( do 


Slightly injured 

do 


No increase of injury, 
do 




|....do 




Mume 


Very slightly injured. 


do 


3 


]....do 


do 


do 




Alexander 


None 


X, 


4 










do 


do 


Three-fourths of leaves 
fallen. 

Do. 

Do. 
No record. 












I 


do 


do 


5 


Willett 

Old Mixon 


do 

do 


do 


6 


do 







CONCLUSIONS, CORVALLIS, ORKO. 

Obxrrvalio)if< — ( 'ontiinuM I . 

TABLE v.— I'LUMS, WITHOI'T LIMK. 

[1 ounce ti> If). r> gallons.] 



29 



Sam- 
ple 
No. 


Variety. 




Injury. 




July 23. 


August 3. 


December 1. 




fliniicrial Kpiiuniso ... 
l.....,o 


None 




Almost entirely defoli- 
ated. 
Do. 


1 


do 


...do 




I....,ln 


do 


..do 


Do. 


2 


|....a» 




do 


Do. 




f....(lo 


do 


do 


Do. 


3 


IWilhiiiu'tti' 


do 


do 


Do. 




f....(l() 


de 


do 


Do. 


4 


1 do .... 


. do . .. 


do 






f do 


..do 


.do 




5 


[ do 


do 


do 


ated. 




(....do 


do 




Do. 


(i 


1 

IKoIh' di' Snriji'iit . . . . 


do 


do 


Do. 











Pl.TMS (\VIT1[ lime). 

Only tliret> trt^cs were sprayed with the solutions inadt' up with '.•.5 
oallons of water, Nos. 2, IJ," and -i txMng used. No (^tl'ects from the 
sprays \\ov{\ to ))e observed on either rJuly 2;> oi' August 8. ()u 
December i tlu^ tirst two were entirely defoliated, whiU; the tree 
ti'eated with No. 4 had only lost a few leaves. 

A luimbei- of varieties were sprayed with the solutions Nos. 1 to <!, 
made up with 15.5 o-allons of watei' to an ounce of tlu L;r(M'n. None 
of the tre(\s show ed any injury on eithei" July 2H or Au<>'ust ;->, but on 
D(H-einber I all werc^ eithei' completely, or almost completely, defoli 
ated. A Heine Claude [)lum tree sprayed wit'i No. 1 and a (JrecMi 
(ra<;e spi'ayed with No. 8 were ainonn' this oi-oup. with n^sults as stated. 

DISCUSSION. 

The observations made on I)eceml)er 1 were for the pui'pose of tind- 
ing' out whether the sprayed trees dropped their leaves earlier in tlu' 
fall than those not sprayed, and whether this premature fallino-, if it 
existed, had any relation to the amovuit of solubhi arsenious oxid used 
on the tree. The time at which the leaves fall ordinarily varies greatly 
with the season and the variet}^ of the tree. Th(^ college orchard con- 
sists of two or three trees each of (juite a number of varieties, and 
when they were examined, on December 1, there was not onh' a sur- 
[)rising- degree of variation in the condition of the foliage of the difl'er 
(Mit varieties but also a great difference between the several trees of 
the same variety. Two apple trees (Waxen) standing side V)y side 
were sprayed with No. 2 plus lime. On December 1 only a few leaves 

" A cherry tree sprayeil witli No. .") without the addition of lime showed no injury 
on July 23 and August 3, and on December 1 it was entirely defoliated. 



80 PARIS GREEN SPRAYIKG EXPERIMENTS. 

had fallen from one of the trees while on the other not over 1(» per 
cent remained. Likewise two trees of the same variety, standing- :;;ide 
hy side in the same row, were sprayed with No. 5 plus lime. When 
examined three-fourths of the leaves had fallen from one and only a 
few from the other. Thus the examination of the orchard failed to 
show that the spray had an}^ etfect whatever upon the falling of the 
foliage. The tabulated data, however, seem to indicate that a some- 
what larger proportion of leaves had fallen b}^ December 1 from trees 
sprayed with Nos. 5 and than from those treated with Nos. 1, ii, 3, 
and 4. Whether this was due to the spra3^s or to mere chance in the 
selection of the trees, it is impossible to say. Little efl'ect if any was 
produced on the apple, pear, and plum trees. 

As to the effects of the various strengths of soluble arsenious oxid 
the results of this set of experiments alone seem to show that vmder 
favorable conditions, such as prevailed at the time the spraying Avas 
done and during the following 30 days, it is safe to spra}' apple, pear, 
and plum trees with any of the 6 samples, both with and without the 
addition of lime. None of the samples injured any of the varieties of 
these fruits sufficiently for the damage to be considered of practical 
importance in orchard work. It may be noted, however, tliat the 
work was done under peculiarly favorable conditions. Probably not 
over 16 minutes elapsed in any case from the time the poison was first 
mixed in the water to the time it was sprayed on the trees, giving but 
a short time for the arsenious oxid to enter into solution, and the 
weather conditions were such that after being sprayed on the trees 
the moisture evaporated very rapidly. Under practical orchard con- 
ditions it would pro])ably be safer not to use Nos. 5 and 6 on apple, 
plum, or pear trees without the addition of lime. 

No conclusions can bo drawn from this series of experiments as to 
the peach trees, as these trees in the college orchard are growing on 
soil entirely unsuited to them. The trees are not thrift}', some of 
them are nearly dead, and it is Ijclieved that the resistance of the foli- 
age of the various trees to the action of the soluble arsenic \aries 
greatly. 

SUMMARY. 

The following table shows the maximum amount of sohible arseni- 
ous oxid in Paris Green which can l)c safely used on th(^. varieties of 
fruit trees included in these experiments. It must be remembered 
when 8 per cent is given as the maximum that this was the strongest 
solution used, and had stronger ones been employed they might have 
been found safe also for such trees as endured the 8 per cent solution 
of soluble arsenious oxid, and these cases are therefore marked "8 -j-." 
If even the smallest amount of soluble arsenious oxid was found to be 
injurious the word " inapplical)le '' is used, since the sample marked 
No. 1 is as pure a Paris Green as can be obtained on the market. 



SUMMARY. 



31 



Amounts of soluble arKcnioiis o.riil (tUonxihle in Paris (Ireen. 
[Samples analyzed by ten-day water-e.xtraction method.] 





Apple. Pear. 


Peach. 


Plum. 


Place of experiment. 


Withont 
lime. 


With 
lime. 


Without 
lime. 


With 
lime. 


Without 
lime. 


With 
lime. 


Without 
lime. 


With 
lime. 


WiishinKtun. \).V 


Per cent. 

8 + 

8 + 

■1 

6 

•1 

4 

8+ 


Per ct. 

8 + 

8+ 
6 

8 + 
7 
() 

8 + 


Per cent. 

8-t- 

8+ 
8+ 


Per ct. 

8+ 

8 + 
5 

8 + 


Per cent. 

Inappli- 
cable. 
....do... 
....do... 
....do... 


Per cent. 
l> 

5 
4 

5 


Per cent. 


Per ct. 


ColleKf I'ark, .Md 


3 


5 


Illiacii.N.Y 

Kingston, R.I 


5 


nurham, N. II 


4 


h-i) 


Cleiu.son College, S. C 






Inappli- 
cable. 


Inappli- 
cable. 


4 


Corvallis, Oreg 


8 + 


8 + . 


8-f 


8-1- 






, 







A stiidv of the wcutlicr cliiirts for the \;ii-ious stations shows that 
the folKjwi no- periods elapsed between tlie dates of s[)i-ayiiiu- and the 
first rainfall: Washington, D. C, about lO da^'s; College Park, Md., 
about \'2 days; Ithaea, N. Y., about 8 days before a very liolit rain 
and tiieii ['.) days before the next rainfall; Kingston, K. I., about 5 
days and then 7 more before another rain; Clemson College, S. C, 
10 days, followed ])y a very light rainfall and a long dry term. It is 
thus seen that in nearly all cases the wc^atlier conditions were almost 
ideal, if the word may so be u.sed, for producing the ma.xiinum damage 
from the sprays. During the rjither long dry period after s))raying, 
w hen only light rains fell, if any, the dow and carbon dio.xid of the air 
acted upon the Paris (xreens, causing them to decompose and set free 
the ai'senious oxid, so that when I'ain linally came a large amount of sol- 
ul)le arsiMiious oxid was present, w hicli tiie leaves absorbed and thus 
caused burning. These conditions were especially striking al Clem.son 
College, where no rain fell for lo days, after which just about enongli 
rain fell for I) days to dissoht^ the soluble arsenious oxid and yet not 
wash it oti'. Another dry period followed, terminated by rains, which 
caused the soluble arsenious oxid to bui'n the foliage. 

Taking tlu' weather conditions into consideration, and judging the 
results in a very conservative maiuier, it would appear from the 
figures given in the table that the following conclusions may ])e di'awn: 

(1) For apple trees sprayed w'ithout the use of lime the amount of 
solulile arsenious oxid^' allowable lies between 4 and s^ ])er cent, a 
fair average being 6 per cent. 

(2) For apple trees sprayed with the us(> of lime the amount of solu- 
ble arsenious oxid allowabh^ is betW'Cen t! and S-f- per cent, a fair 
average being 7 per cent. 

(3) For pear trees sprayed without the use of lime the amount of 

"By soluble arsenious o.xid is uu-ant the amount extracted from 1 part of Paris 
Green by 1,000 parts of carbon flioxid-free \va.ter during the course of 10 days. 



^'A 



32 



PARIS OREEN SPRAYING EXPERIMENTS. 



soluble arsenious oxid allowable is between 3 and 8+ per cent, a fair 
averao"e being (3 per cent. 

(■i) For pear trees sprayed with the use of lime the amount of solu- 
ble arsenious oxid allowable is between 5 and 8+ per cent, a fair 
average being 7 per cent. 

(5) For plum trees sprayed without the use of lime the amount of 
soluble arsenious oxid allowable is between 3 and 8+ per cent, a fair 
average being about 4 per cent. 

(6) For plum trees spra3^ed with the use of lime the amount of solu- 
ble arsenious oxid allowable is between 4 and 8+ per cent, a fair aver- 
age being from 5 to per cent. 

(7) In spraying peach trees none of the Paris Greens bought upon 
our market should be used without the addition of lime. 

(8) For peach trees sprayed with the use of lime the amount of solu- 
ble arsenious oxid allowable lies between 3 and 6 per cent, a fair aver- 
age being 4.5 per cent. 

(9) The diti'erence in the effect produced ])y Paris Greens used with 
and without the addition of lime is so great that lime should always be 
employed. 

For ready reference these conclusions are also embodied in the 
followinsjf table: 



Maximam and averdge amounts of soluble (trsenions oxid (illowahk. 



Apple. 


Pear. 


Without lime. 


With lime. 


Without lime. With lime. 


Limits. 


Average. 


Limits. 


Average. 


Limits. 


Average. Limits. 


Average. 


Per cent. 
4-8-^ 


Per cent. 
6 


Per cent. 
6-8+ 


Per cent. 

7 


Per cent. 
3-8+ 


Per cent. Per cent. 
6 5-8+ 


Per cent. 
7 


Peach. 


Plum. 


Without lime. 


With lime. 


Without lime. 


With lime. 


Limits. 


Average. 


Limits. 


Average. 


Limits. 


Average. 


Limits. 


Average. 


Per cent. 
0-0 


Per cent. 



Per cent. 
3-6 


Per cent. 
4.5 


Per cent. 

3-8+ 


Per cent. 
4 


Per cent. 

4-8 + 


Per cent. 
6 



It is evident that the amount of soluble arsenious oxid allowable in 
a Paris Green depends largel}^ on the kind of fruit tree that is to be 
sprayed. The author is of the opinion that State chemists should not 
select any fixed standard by which to judge all Paris Greens sent in 
by the farmer, but should find out for wiiat purpose the green is to 
be used and base his decision on the resisting power of the kind of 
tree to be sprayed. It would perhaps be advisable to have a printed 
form giving the names of the various common fruit trees and to state 
after each whether or not the sample sent could be used upon it. 



U 



H 181 84 



r 

is.. 



\J. 






P 









/^..^ 



V 



^-^^' 



y 



1 • o. 



t:7- jp 



a^ -^1 









f" 



O H O 






^ .,.• ^^ °^ *°''° A^ ^ "'^ ^ 

.. O N « x^. 























HECKMAN 

BINDERY INC 











SEP 84 

N. MANCHESTER, 
INDIANA 46962 






'iiiiiiiilmiiiiji; 
iiiiJiWii.'iijiiid 




' 






